Spectral Types of Field and Cluster O-Stars

Abstract

The recent catalog of spectral types of Galactic O-type stars by Mai'z-Apella'niz et al. has been used to study the differences between the frequencies of various subtypes of O-type stars in the field, in OB associations and among runaway stars. At a high level of statistical significance the data show that O-stars in clusters and associations have earlier types (and hence presumably larger masses and/or younger ages) than those that are situated in the general field. Furthermore it is found that the distribution of spectral subtypes among runaway O-stars is indistinguishable from that among field stars, and differs significantly from that of the O-type stars that are situated in clusters and associations. The difference is in the sense that runaway O-stars, on average, have later subtypes than do those that are still located in clusters and associations.

arXiv commentTo be published in the October 2004 issue of the Astronomical Journal Included Figure 1, page 9

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• The young stellar population of NGC 4214 as observed with HST. II. Results
• The Initial Mass Function of Field OB Stars in the Small Magellanic Cloud
• The stellar population of the star forming region G61.48+0.09
• Astrophysics in 2005
• Kinematics of the Central Stars Powering Bowshock Nebulae and the Large Multiplicity Fraction of Runaway OB Stars